nscommon: move to separate file

It's really awkward spilling the ns common infrastructure into multiple
headers. Move it to a separate file.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

2 files changed, 22 insertions, 1 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index b807516a1b43..1f48f7cd2d7b 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -8,7 +8,7 @@ obj-y     = fork.o exec_domain.o panic.o \
 	    sysctl.o capability.o ptrace.o user.o \
 	    signal.o sys.o umh.o workqueue.o pid.o task_work.o \
 	    extable.o params.o \
-	    kthread.o sys_ni.o nsproxy.o nstree.o \
+	    kthread.o sys_ni.o nsproxy.o nstree.o nscommon.o \
 	    notifier.o ksysfs.o cred.o reboot.o \
 	    async.o range.o smpboot.o ucount.o regset.o ksyms_common.o
 
diff --git a/kernel/nscommon.c b/kernel/nscommon.c
new file mode 100644
index 000000000000..ebf4783d0505
--- /dev/null
+++ b/kernel/nscommon.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/ns_common.h>
+
+int ns_common_init(struct ns_common *ns, const struct proc_ns_operations *ops,
+		   bool alloc_inum)
+{
+	if (alloc_inum) {
+		int ret;
+		ret = proc_alloc_inum(&ns->inum);
+		if (ret)
+			return ret;
+	}
+	refcount_set(&ns->count, 1);
+	ns->stashed = NULL;
+	ns->ops = ops;
+	ns->ns_id = 0;
+	RB_CLEAR_NODE(&ns->ns_tree_node);
+	INIT_LIST_HEAD(&ns->ns_list_node);
+	return 0;
+}